Certain embodiments of the disclosure may include systems and methods for variable speed operation of combustion engines. According to an example embodiment of the disclosure, a method is provided for controlling the operation of the combustion engine. The method can include providing power from a power source to a converter; providing frequency variable power to a generator from the converter; accelerating the generator and associated turbine to a predetermined speed by modulating the frequency variable power from the converter; after a predetermined turbine speed is achieved, disconnecting power supplied to the generator by the converter; and modulating the subsequent operation of the generator using power from the converter.